冷蕨 leng jue

Polypodium fragile Linnaeus, Sp. Pl. 2: 1091. 1753; Aspidium fragile (Linnaeus) Swartz; Athyrium fragile (Linnaeus) Sprengel; Cyclopteris fragilis (Linnaeus) Gray; Cyste fragilis (Linnaeus) Dulac; Cystea fragilis (Linnaeus) J. Smith; Cystopteris filix-fragilis Gilibert.

Rhizomes shortly or long creeping, scaly at apex and stipe bases; scales brownish, broadly lanceolate. Fronds approximate or caespitose; fertile fronds (3.5-)20-35(-49) cm; stipe brown at base, upper part stramineous or chestnut-colored, usually shorter than lamina, nearly 1/3-2/3 as long as lamina, occasionally slender and slightly longer than lamina when plant in crevices, 5-14(-20) cm, (0.2-)1-1.5 mm in diam., with sparse, shiny scales; lamina usually 2-pinnate to 2-pinnate-pinnatifid, occasionally pinnate or 3-pinnate, lanceolate to broadly lanceolate, 17-28 × (0.8-)4-5(-8) cm, shortly acuminate at apex; pinnae 12-15 pairs, ascending, basal 1 or 2 pairs slightly shortened, or nearly not shortened, ovate to ovate-lanceolate, (0.4-)2-4(-7) × (0.2-)1-2.5 cm, obtuse or shortly acuminate, toothed at apex, subopposite, subsessile, widely separated from each other, usually 1-2 × as long as wide, 1.5-4.5 cm apart, base parallel to rachis on acroscopic side, ± cuneate on basiscopic side; pinnules 5-7 pairs, ovate or oblong, acroscopic side truncate, basiscopic side cuneate at base, sessile or shortly stalked, entire or toothed at margin, or pinnatifid, rounded or obtuse and toothed at apex; middle pinnae similar to lower pinnae, but slightly longer, separated from each other by 1.2-2.5 cm, subopposite or alternate, subsessile; upper pinnae pinnatipartite, toothed only on apices and acroscopic margin; veins pinnate, costules slightly tortuous, terminating in entire teeth. Lamina herbaceous when dried, green or yellow-green. Rachis and costae, especially their bases, ± with sparse unicellular to long multicellular hairs, even with few scale hairs. Sori small, orbicular, medial on veins, 2-4 pairs per pinnule, 1 or 2 sori at acroscopic side in upper pinnules; indusia pale green or brownish, ovate to lanceolate, membranous. Spores dark brown, perispore surface with regular, denser spines. 2n = 84*, 168, 252, 336.

Under alpine shrubs, in rock crevices on shaded slopes, base of rocks, damp areas at streamsides; (200-)1500-4500(-4800) m. Anhui, Gansu, Hebei, Heilongjiang, Henan, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, W Sichuan, Taiwan, Xinjiang, Xizang, Yunnan [Afghanistan, India, Japan, Kashmir, Korea, Mongolia, Nepal, Pakistan, Russia; Africa, SW Asia (Iran, Turkey), Europe, North and South America].

According to Knapp (Ferns Fern Allies Taiwan, 445. 2011), Windham described several cytotypes for Taiwan (diploid, tetraploid, and hexaploid) in 2007; thus, further study of the taxon is pending. Many infraspecific taxa have been described from Europe.